AC72 Oracle Team USA Spaceship has landed

Also, the main L-foils at that high negative angle of attack must have produced a lot of drag and contributed to slowing the boat, so in addition to pulling the whole boat down, they contributed to the torque loads that forced the bows down.

It will be interesting to see what design changes come out of this. I'm picturing main foils with super strong hinges so that the L-foil part swings to near vertical when top loaded, and back to horizontal under normal upward loads. I wonder if such a thing is possible with modern materials, and if the drag and weight of such a hinge would be acceptable. It would not be an angle of attack control per se, so it seems like it might be acceptable under the rules.

We all have had the same problem at every bear away, think A mark in a good blow, many times with the same results (pitchpole).

As you turn from going upwind to downwind, you've got several additional forces all happening at once, to include the centrifical force the rig exerts as it's being swung in the big arc, the added drive from the (momentarlily, until you accelerate) greater aparant wind which is now puhsing the bows down, not lifting the windward hull up, and the added drag of going faster, on the boards which also pulls the bows down, until they get into foiling mode.

From watching that video several times, it looked like a classic bear away nose dive. As they bear away and unroll the jib, the bows go down and never really come back up...they just keep going deeper and deeper as they accelerate, until it's too deep to recover. Use full screen to see this:

http://www.youtube.com/watch?v=drgglIebuQY

On our boats, we can all run to the back, to keep the bows up when we get to A mark and we know it's coming, but they can't shift as much (relative) balast aft, as we do in that situation.

I still think it needs more volume in the bows to help prevent this nose diving. That was the cure for the early Blades, as well as some of the A cats.

You may recall years ago, when the mega cat Playstation had to have it's bows modified, enlarged, etc. The first time they took it out in big wind and waves, they also stuffed the bows and nearly pitched it right over.

The only beach cat I've felt 'safe' on in a big wind bear away was the Inter 20, and it's known for it's huge, fat bows. When I look at the design of the AC72's, I see A cat like, skinny bows. Great for keeping weight off...but not so good for preventing a picth pole.

Remember, they cannot simply 'dump the main' when it gets blowing too hard and you want to bear away, like we can. If they are going to keep going out in 25knots, they'll need bigger bows, or a much better righting system!

It looked very similar to this earlier pitchpole, on the 45' version, nearly identicle;

http://www.youtube.com/watch?v=-KNql99zT6s

Now, watch this next video of the first sail of Oracle 17. Pay particular attention to what the bows are doing, they always seem to be pointing down. Near the end of the vid. at 1:50, they are just cruising back to the dock, not pushing it, not even blowing too hard, but going downwind, and the bows are looking like they want to dive.

http://www.youtube.com/watch?v=Sr055W97l4o

Go to 'full screen' you'll have a better look.

the recovered platform looks a lot better than it did after it had turtled and was filling as it disappeared off into the pacific night

I can hear them on the docks now:

Hey...get some Duct Tape! And HURRY!

http://www.youtube.com/watch?v=JLX1XPCQodk
In this video it looks like OR-S is the only AC45 in the group letting out the wing on the bear away. I wonder if the AC72 had the same wing trimmer.

They are adjustable. They can adjust the angle of attack. There is a learning curve here and they missed the setting for the conditions at hand. If you check out Sailing Anarchy ,Tide Tech shows that the conditions changed when they made that last bear away. Had they had the time or knowledge to set the foil properly they may have been alright.

They are not counting on forward buoyancy to keep the bows up. They are counting on the foils for that.

So is the lesson then to travel-in when starting to stuff as the apparent wind shifts aft? Part of that makes sense, but when the apparent wind is at 90°, It would be really tough to override the instinct to dump the traveller. Not sure I'd have enough time to think about it...

Past a certain point, you are just screwed. IF you can keep your speed up through the turn you are better off as you apparent wind will remain more forward. When the boat stuffs hard enough to go over, I don't think anything you can do will save it. Sail in, sail out, it's only going to change the angle with which the mast hits the water. Once it stuffs, the momentum and wind pressure are working against you and you have no helm. I've been out where it took three or four attempts to bear away to get through the turn. The trick was to get through the turn as fast as the foils would let you when the waves and wind are just right. The faster you can make that turn, the better off you will be. Get your speed as fast as possible, hang on, and yank it through hopefully just short of your rudders stalling.

These guys were just hugely overpowered and as they bore away, the rudders were probably stalled and about 1 second later and another second after that, there wasn't enough rudder in the water to have any influence over the direction of the boat.

That wing is ONE HUNDRED AND THIRTY FEET TALL!!! That's a lot of tomahawk momentum!

There was a thread on here a long time ago about a guy that made a CO2 cartridge with balloon that you could inflate to stop a mast turtling, would something like that have stopped this wing filling with water which stopped the righting?

... you can buy one. Just search for: Secumar Auto Inflation Anti-Inversion Mast Float

Somehow not very common. I've never seen a boat equipped with it. Propably because getting a beach cat out of the 100% turtle position by manpower is not so difficult, as far as the boat is not too wide like Tornado, H21, or others.

That

airbag-recovery

could work on any boat I guess.

Fill the wing with helium....

So. How much money is uncle larry going to have to shell out to get this beastie back on the water? Any guesses?

What did he spend on the last AC, something like $360M wasn't it? I have buyers remorse spending $200 on a pair of jeans. lol

Somewhere I read this boat cost about $10 Million. Peanuts to Larry.

Oh, but you can still use your $200 jeans...right?

I don't think so he seems to have a duty problem.

He doesn't wear any trousers. Check his avatar.

Is that supposed to be Karl?

And all this time I thought it was the crew of Oracle 17 abandoning the boat!

He just bought our neighbor island for $500-600 mil. The repair cost will probably come out of his walkin' around money.

I can't even fathom that level of wealth. The man plays at a level that basically beyond comprehension.

He could have his own private space station orbiting the Earth.

No, he's more into Japanese Botanical Gardens.

who says he doesn't?

After watching the video (http://www.youtube.com/watch?v=drgglIebuQY) I think they buried the windward bow first. Can anyone confirm my observation?
If this in fact happened it is possible that someone just dialed too much angle of attack to the leeward foil or not enough AoA to the leeward one.

I have it on a relatively high authority that after the big wave of water rushed over the deck, there were only 2 people left on the boat for the ensuing pitchpole.

and now it seems artemis broke the main beam on their ac72 by tow testing it....

Luna Rossa to launch their ac72 this week

if it's been built as well as it's sister ship they should be up and flying in no time

The Whole Story

The trimmer said, "as the bows went down, I crawled as far forward as i could.

- I guess it's the same on all boats... it's the crews fault we capsized.

HAH! +1 on that <img src="<>/smile.gif" alt="smile" title="smile" height="15" width="15" />

Latest AC72 entry

Launch

Man that thing is gonna be blinding people.

No kidding - they sure put that new flexible chrome vinyl to the test. That stuff is about $1,600 in material alone to do an F18.